How to put all unlinked nodes to the right?

Question

digraph
{
    rankdir=LR

    a -> b
    c -> b
    b -> d
    e       // unlinked node
}

There are some nodes which are not linked to any of the other nodes in my dot file. Without explicitly using rank to define those nodes, is there any graceful way to put them to the right most position since it is a hard work to reparse the whole relations for finding them out and it is almost impossible to figure it out the maximum depth of the generated graph due to the opaqueness of node rearrangement policy?

Answer 1

You could put the unlinked nodes in a subgraph and use rank="max" to achieve this:

digraph
{
    rankdir=LR;
    a -> b;
    c -> b;
    b -> d;
    { rank="max";   e; }
}